A conventional computer generally includes a rectangular case, a large-area motherboard secured inside the case, a plurality of functional sub-boards set on the motherboard, and a power supply, hard disk drive as well as optical disk drive etc. secured inside the case.
However, the area or volume of the motherboard in the conventional computer is very large. Thus, the area or volume of the conventional computer is very large. Furthermore, the connectors for electrically connecting the components mentioned above are variously arranged according to the design of different manufacturers. Hence, it is difficult for users to assemble a computer with the components mentioned above. Moreover, when it is necessary to replace any component, such as the sub-boards or hard disk drive, inside the case, the procedures to disassemble and re-assemble the components are troublesome.